ABSTRACT
Knowledge of the biochemistry of the filarial worms is scantier than that of the other helminth groups. As Barrett points out, filarial worms are species specific for their definitive hosts and, of the ones that infect humans, only Brugia malayi can be cultured in the laboratory in an alternative host. This difficulty has diverted attention to other filariae as possible models for human filariasis, and Dirofilaria immitis has received its share of attention. Adult D. immitis, like other filarial worms, has a functional digestive tract, which has been observed to contain host erythrocytes. D. immitis possesses all the enzymes of glycolysis and the tricarboxylic acid cycle, although the activities of aconitase and isocitrate dehydrogenase are low and probably rate limiting. A lipid analysis of D. immitis shows that the major lipid classes are the sterols and their esters. Acid proteases are widespread in helminths, irrespective of host or site of predilection, and also occur in D. immitis.
